This invention relates generally to the field of hand tools, and more particularly to an improved form of screw holding device engaged with a conventional screwdriver to facilitate the installation of screws in areas of limited access often using only a single hand of the user. Devices of this general type are known in the art, and the invention lies in specific constructional details which permit improved operation due to superior support for the screw as it is driven.
The great bulk of the prior art usually includes the provision of a pair of resilient fingers adapted to grasp the screw at the underlying surface of the head. The fingers are carried by a sleeve in turn carried by the shank portion of the screwdriver and frictionally retained thereon. Typical of such structure is the disclosure in U.S. Pat. No. 1,426,320 to Reid.
Naugle et al., Pat. No. 1,512,706 granted Oct. 21, 1924 discloses the structure of a screw supporting sleeve which is threadedly engaged with a corresponding thread on the screwdriver shank. The driven screw is supported only at the head thereof.
Greet, Pat. No. 1,549,413 discloses a resilient metallic stamping which engages the under surface of the head of a screw, and a short segment of the threaded shank disposed immediately therebeneath. It employs the under surface of the head of the screw to spread the resilient sleeve to release the screw as it nears the position of full seating. This is also the case in Josepho Pat. No. 2,406,952 of Sept. 3, 1946.
Duggan, U.S. Pat. No. 2,780,257 of Feb. 5, 1957 employs a pair of tubular coaxially arranged members, an outer one of which is used to tense an inner one as the screw is driven to full seating. Actual engagement of the screw is by the head portion only, although the inner tubular member surrounds at least part of the shank of the screw as well without contacting the same.
Lowry, Pat. No. 2,954,809 of Oct. 4, 1960, discloses a clamping device of sleeve type in which the broadened blade of the screwdriver is used to open the clamp.